That looks like an Original or an A150.
If it’s a Snapmaker Original, you should be posting in its dedicated forum, and the information on linear module pitches does not apply to you (the Original’s modules are all the same pitch as far as I know).
If it’s an A150 with the newer linear modules, the pitch information is included in the labels. There’s a good photo in Skreelink’s post here: Fitting new linear modules - #2 by Skreelink —see the bit where it says “Lead 20mm”? One module will say “Lead 08mm” (I think) instead. That one is supposed to be the Z-axis module.